You should check the following sites:

* http://www.linmodems.org/
* http://www.physcip.uni-stuttgart.de/heby/ltmodem/
* http://www.cixel.com/elinux/t21.htm

If it is lucent one limodem, I remember you only need to download the source
and run "debuild -r fakeroot", then it will build the debian package for you.

You can also check http://www.linux-on-laptops.com/
it collect the link of many sites talk about how to install Linux on laptop